I. Field of the Invention
This invention relates generally to an apparatus to facilitate the loading and unloading of ladders onto and from the roof of road vehicles and, more particularly, to an improvement over the prior art that reduces the height profile of such apparatus to thereby decreases wind resistance and allows entrance to certain work sights having height restrictions.
II. Discussion of the Prior Art
The closest prior art to the present invention are U.S. Pat. Nos. 5,297,912; 6,427,889 and 6,764,268 to Avraham Y. Levi. Each comprise front and rear 4-bar linkages. In each, a first stationary bar is adapted for attachment to the vehicle's roof and a second movable bar is pivotally joined to the stationary bar by a pair of linkages. An elongated shaft is journaled for rotation in the stationary bars of the front and rear 4-bar linkages and one of the pair of linkages is clamped to the shaft whereby rotation of the shaft results in the rotation of the movable bar on which the ladder(s) being transported are disposed from their position atop the vehicle to a position straddling the side of the vehicle where it is within reach of a workman on the ground.
In each of these prior art designs, the movable bar rests atop the stationary bar when the load is located on the vehicle's roof. This stacked relation of the stationary and movable bars necessarily adds to the overall height of the ladder load while being transported. The height above the vehicle's roof not only results in greater wind resistance and noise at higher speeds of the vehicle, but there are also job sites, like parking garages, that have height restrictions that may be violated.
It is therefore a principle object of the present invention to modify the ladder racks of the prior art so as to reduce the overall height of the ladder rack mechanism by over 50%.